Method of cracking oil



Feb. 8, 1927. 1,616,521

F. E. WELLMAN METHOD oF-CRACKING OIL Original Filed March 20. 1923 2 Sheets-Sheet 1 'f 1 616,521 Feb. 8 1927. F. E. WELL-MAN METHOD OF CRACKING OIL Original Filed March 20, 1923 2 Sheets-Sheet 2 Patented Feb. s, 1927.

UNITED STATES 1,616,521 PATENT OFFICE.

FRANK E. WELLMAN, 0F KANSAS CITY, KANSAS.'

METHOD OF CRACKING- OIL.

Original application filed March 20, 1923, Serial 170.626.386. Divided and this application led May 7` I 1923. Serial No. 637,255.

lIhe present application is a division of my copending application ySerial No. 626,386, led March 20, 1923. l

My invention 'relates to cracking processes and especially to the cracking' of hydrocarbons of high boiling point to produce hydrocarbons of low boiling point suitable for motor fuel.

`Among the objects of the invention are to reduce the deposition of carbon on the still walls, to increase the amount of oil that can be treated in an apparatus of given content before it becomes necessary to shut down in order to clean out carbon deposits, ,and v to effect an economical improvement in the ratio of yield and quality of product. Other objects will appear from a perusal of the following specification and drawings accompanying the same.

In the drawings, which illustrate a preferred form of apparatus for carrying out my invention:

Fig. 1 is a vertical section through the center of the still taken on the line 1-1 of Fig. 2 with the tubes back of the plane of the section omitted for the sake of clearness; f

gig. 2 is a top plan view of the apparatus; an

Fig. 3 is a transverse or horizontal section taken on the line 3-3 of Fig.'1.

Referring to the drawings in detail, 1 deS- ignates a cylindrical furnace or vheating chamber in which is mounted a circular 'series of vertical cracking tubes 2 arranged around the inside of the furnace wall and .slightly spaced therefrom as shown in Figs.

1 and 3. The tubes are L-sliaped with the bottom 3 of each tube projecting out through. and beyond the furnace wall where it is" flanged and capped on the end as indicated at 4. The upper ends of the tubes 2 extend up through the furnace cover 5, and are capped as indicated at 6. vThus all the capped ends of the tubes are'outside of the furnace. To take vapor off from the oil while preventing the oil from foaming over into the vapor line, vaporizing drums 7 are provided around the top of the furnace, each of which is connected with several of the cracking tubes 2 and a common Vapor line 8, in the present embodiment, the sixteen cracking tubes being por/tioned among the four vaporizlng drums in groups of four connected to the drums through pipes 9, see Figs. 1 and 2.

Near the outer ends of the bottom portions 3 of the cracking tubes, connection is made outside the furnace between the lcracking tubes and a manifold 10, extending around the furnace in the form of a split circle or C with the ends 11 and 12 of the C-form closed or capped as indicated at 13 and 14. Outside circulating pipes 15 connect the vaporizing drums 7 below the liquid level, with i comes the supply connection and pipe 17 the 'draw off, the rate of supply and 4 draw off` being controlled by valves 20 and 19, re- 80 spectively. Obviously an ,interchange of function between pipes 16 andl? will be effected uponv a reversal of the setting of the"y Vvalves 18, 19, 20 and 21.

To enable a' return distillate such as the redux from a fraction'ator, to be fed into the still along withthe supply, a conducting pi pe 23 for such return distillatel is connected to both pipes 16 and 17Jthrough suitable Swiching valves 24 and 25rbetw'een the still and the valves 20 and `421.

Heat is imparted to the crackingtubes within the furnace by a rotating source of heatin the form of a rotatino burner 26, sinilar tozthose of my co-pending applications Serial No. 523.062 filed December 17,

1922.V In the present arrangement the burn cr 26 is supplied with fuel and air through the' fuel and air pipes 27 and 28 respectively, 100

32'and `driving pulley 33 connected with a 105 d suitable source of power, not shown. The

bottom'stationary part 34 of the swivel coupling is supplied with fuel andair through the stationary lead-in pipes 35 and 36, provided with valves 37 and 38, respectively. 11o

1921 and Serial No. 532,873, filed January 30;" i

For properly1 distributing the hot gases through the furnace and among the cracking tubes, I provide a set of batlles 39 supported by a rod 40 hung from the furnace cover 5 while for producing the required draft through the furnace a stack 41 is provided with which the upper portion of the furnace chamber eoniiects'through pipe 42.

In the operation of the still to carry out the preferred cracliig process, the still is first charged, through one of the pair of pipes 16-17, for example pipe 16, by way ofsupply pipe 22, valve 20, pipe 16 and man- `iifold'10, to the working level as indicated at rwhitch charge may or may not be warmed or preheated. The burner 26 is then put iu operation and the oil in the cracking tubes brought up to the desired'` cracking temperature. Vapors liberated from the oil in the vaporizing drums 7 are conducted oif through the vapor line 8 to suitable fraetionating, condensing and receiving devices, not

shown, but which may be of any known or other suitable type, while enough make-'up is pumped in by Way of the manifold 10 and pipe 16, to, maintain the working level 43. After the make-up amounts to the original charge, residuum is drawn off and make-up or fresh oil is supplied at twice the rate of evaporation so that the amount Withdrawn in vapor form aswell as the residuum drawn o'ifis thereby compensated for, and a slibstanially constant amount of oil is maintained in the still. By governing these three.

' diate distillates such as the reflux from a fractionator, are returned to the still along with the `oi1 supply by wa of the return distillate ipe 23, valve 24, pipe 16 and inanifold l0. Vhen the run is half over the flow of supply and residuum draw-.off is reversed by reversing the setting of the valves, thatvis by closing valves Q0, 24 and 19, and opening valves 21, 25 and18.,

The carbon deposit is thickest at the end Where thel residuum is drawn off and graduates down to nothing at the point where charging is started. Thus by reversing the flow in the manner described, a fairly even deposition of carbon on the diiferent tubes is brought about, resulting in a delay of the Anecessity Ior a shut-down for cleaning.

In one reduction to practice of the present invention, in which theA outfit comprises eight three-inch tubes and eight four-inch tubes with tenl feet in the furnace, I haverun sixty gallons an hour with very good results. In running this outfit, fifty barrels are put through before shutting' down for cleaning, with a yield of 40 per cent (S0-G1 degree gasoline based on the gas oil charged.

A larger still, under construction, de-V signed to handle a run of 750 barrels of oil before shut-down, is expect d in practice to crack 1,000 barrles before shut-down, due to the relation between the contents and walls being entirely different.

Having thus described my invention, what I claim and` desire to secure by Letters Iatent is:

l. The method of cracking oil which consists in heating the oil in a still, taking off the vapors and at the same time suppl ing fresh oil to the still and drawing o siduum at different points, and reversing the said points of supply and residuum draw-off during the said heating and tak-y ing oft' of vapors,

2. The method'of cracking-oil which consists in charging a given amount of oil into a still at a given point, heating the oil and taking olf the vapors while supplying additional fresh oil at sufficient rate to maintain substantially the said given amount of oil in the still until said additional fresh oil amounts to substantially the original charge, then supplying fresh oil at twice the rate of evaporation and maintaining substantially the said given amount of oil in the still by drawing 0E sufficient residuum at another point and reversing the said pointsof supply and residuum draw-ofi' during the said heating and taking olf of vapors.

3. The method of cracking oil which consistsin 'chargin a given amount of oil into a still or retort, eating the oil to the desired cracking temperature and taking off the vapors, While supplying additional fresh oily at suiicient rate to maintain substantially the said given amount of oil in the still until said additional fresh oil amounts to substantially the original charge, then drawing off residuum and supplying fresh oil at a rate sufficient to maintain substantially the said given amount of oil in the still until a 'given total amount of oil has been treated, the points of entrance of fresh supply into the still and of draw-off of residuum therefrom being interchanged after substantially half the said given total amount of oil has been treated. i 4. The method as claimed in claim-1 in addition to which a portion of the vapors taken olf is condensed and returned to the still with the supply of fresh oil.

5. The method as claimed in claim 2 in addition to which a ortion of the vapors taken olf is condensed) and returned to the still with the supply of fresh 'oil. l

6. The method as claimed in claim 3 in addition to which a portion of the vapors taken oif is condensed and returned to the still with the supply of fresh oil.

7 The method ofcracking oil as claimed in claim 3 in addition to which the oil is caused to circulate by convection from a point below the liquid level near the point of vapor take-oli through a relatively cool zone to the heated bodv of oil along with the said fresh oil supply.

8.` The method of cracking oils which consists in causing the oil to circulate by convection upwardly through a heated zone, into a second relatively cool zone, and return downwardly through a third zone back into the heated zone` taking oi the vapors at a point near the uppermost point inthe cycle of circulation, and at `two different points near the lowermostl point in the 'cycle of circulation continuously drawing off re- `-siduum and supplying additional fresh oil at `a rate suiiicient to compensate for the signature.

FRANK E. WELLMAN. 

